Switching mode power supplies are used in various applications. Multi-mode control is widely adopted in switching mode power supplies because of the high conversion efficiency. Generally, the multi-mode control comprises a pulse skip mode, i.e., the so-called burst mode. However, if the switching mode power supply is under burst mode, the equivalent frequency becomes very low, which may generate audible noise if the equivalent frequency is lower than 20 kHZ. Thus there is a need to provide an improved switching mode power supply that can at least reduce or eliminate the audible noise under burst mode.